Transmission of pictures



Jan. 15, 1929.

C. A. CLARKE TRANSMISSION .OF PICTURES 2 :ShoctsShoot l la er/fan" FiledAug. 8, 1925 Cara/e A 6700?! 1 4 17/};

Jan. 15, 1929.

c. A. CLARKE TRANSMISSION OF PICTURES Filed Aug. '8, 1925 2 Sheets-Sheet2 Patented Jan. 15,1929.

uNirEo STATES PATENT OFFICE.

canon: a. enema, or MONTREAL, QUEBEC, enema, assrcnon r wnsrnmw mewecomm, mconrom'rnn, or NEW YORK, 1v. 2., a conroaurron or new YORK.

TRANSMISSION OI IICTURES.

Application med August a, 1925. Serial No. 48,989.

This invention relates to transmission systems'and more particularly tothe transmission of pictures by electrical means.

In the transmission of pictures, 1t has been found necessary anddesirable at times to transmit the same picture a number of times .tovarious stations and over different transavailable at any maintain afile of pictures availablefor immediate use at a central station or incase lines or channels or. at different speeds of adequately suited toany particular signal-'- ent invention pictures are to be retransmittedfrom a central distributing station over a number of transmission. Thiswill enable the operator at the distributing station to transmit overany available transmission channel or to adapt the speed of transmissionto that most mg circuit.

Obviously, considerable saving of time re-. sults from the use of such amethod as it eliminates the procedure of photographing the subject to betransmitted and the operations incident to its being made suitable for 1i For the purposes of this case it has been transmission purposes.

'One of the principal objects of the. presis the recording of signalsfor retransmission. 1 1

Another object of the invention is there'- nals to reproduce a pictureat a distant sta tron. i In methods of carrier j current picturetransmission heretofore developed, the reproduced picture is .a goodreproduction of the original, but if magnified, it will be seen that thevariations in tone value at the carrierfrequency are not sinusoidal incharacter. In order to retransmit such a'picture it must be treated aswas the original. In accordance with this invention the variations justmentioned. are made to beef, a sine wave character andan electric,carrier wave, of sine form 18- generateddirectly therefrom -forretransmissionpurposes. :It -isa further object of this inventiontoproduce a record from which a sinusoidal carrier wave may be directlyproduced' According to one embodiment of the invention thecharacteristics of each elemental area of a picture are transmitted asmodula tlons of a voice frequency carrier wave whlch can be readllytransmitted over ordi-Y nary telephone lines. The modulated carrler waveis impressed at the distant station on an electrical recorder whichfunctions to .record not only the carrier wave modulated in accordancewith the tone values ofthe picture, but also a carrier wave to be laterinvention will be illustrated and described as employed in connectionwith a picture transmission system such as that disclosed in Patent No.1,606,227, issued November 9, 1926, to Messrs; Horton, Ives. and Long.

thoughtsuflicient to show only so much of the ,apparatus and mechanismdisclosed 1n that application as is necessary to a clear and accurateunderstanding of the present invention. 1' Referring novr'to thedrawing:

Fig. 1 illustrates one form of sending equipment of a picturetransmissionsystem connected by means of any-suitable trans mittinmediumj to a recording mechanism locat at a distant station. n

mechanism at a distant station 'for retransmitting stored si nals.

Fig. 2 illustrates one form-of reproduciug f I Fig. 3 is a si e view ofthe; recording mechanism.

' Fig. 4 is a corresponding f view of the re- .5

producing mechanism.

Fig. 5 is a 'circui diagram illustratinga further use of the invention.7

Referring now to 1, station A although the invention is capable of usein connection with radio oinanyother electrical signaling system. Atstation A there is locatedsuitable mechanism for the trans mission ofcarrier current waves modulated in accordance with the tone values ofthe elemental areas of a picture to be transmit ted. At station B, thereis shown an electrically opera-ted recorder which responds to thecarrier current waves transmitted from station A for recording on arecord representations of the transmitted carrier cur rent Waves. Therecord shown is in the formof a wax cylinder and is preferably of thetype in which the impressions in the wax are lateral cuttings asdistinguished from the hill and valley type of record.

At station A a modulator 6 is supplied with carrier waves from a carrieroscillator 7' and with picture current from a photoelectric'cell 8. Forthe purpose of clearness the modulator is shown in conjunction with anamplifier serving to amplify the picture currents before being impressedon the modulator. Modulated carrier waves from the modulator 6 areimpressed upon the telephone line 10 through a picture channel filter 9and a terminal repeater 11.

The photo-electrc cell8 is located within a transparent drum 14 which isdriven by a shaft 15 to which it is rigidly secured. The shaft 15 isjournaled in a carriage 16 slidably mounted upon a stationary raclr 17.Secured to the shaft 15 is a gear wheel 18 which meshes with the teethof a gear 19 secured to a shaft 20. The shaft 20 is threaded for aportion of its length and engages threads formed in one of the uprights16 so that upon the rotation of shaft 20, a rotary and a lateralmovement is imparted to the drum 14. Motive power is supplied to theshaft 20 from amotor 21 preferably of the phonic wheel type through afriction clutch or starting mechanism 22. The starting mechanism 22 isarranged to control the engagement and disengagement of the parts of thefriction clutch, thereby controlling the starting and stopping of the Itransparent drum 14."

Mounted on the transparent drum 14 is a transparent film of the pictureto be transmitte Light from a source 30 is focused by means of a' lens31 upon the film through whichdt' passes to the photo-electric cell 8.The amount of light affecting the photoelectric cell 8 is determinedby-the light density of the elemental area of the film which is at thatinstant in alignment with the light source 30. The amount of lightfalling upon the hoto-ielectric' cell 8 in turn determines t e amount ofcurrent which is supplied to the amplifier modulator 6 and inconsequence, the value of current impressed on the line conductors 10,or in other words the amplitude of the carrier wave. The master fork 25not only serves to control the current driving the motor 21 but alsoserves to control the application of a separate and distinctsynchronizing current wave through control channel filter 27 and theterminal repeater. 11 on the condtictors 10 extending to station B.

The modulated picture carrier wave and the synchronizing carrier wavetraverse the line 10, the terminal repeater 33 and the amplifier 34 andare impressed directly on the operating coil 35 of the electricallyoperated recorder 36.

Referring now for the moment to Fig. 3, there is shown diagrammatically,an electro magnetic phonograph recorder having a per-- manent magnet 38,although an electromag' net may serve equally well. Secured to themagnet 38 are soft iron pole pieces 39-l-0 and 4142, preferablylaminated, with beveled ends between which is pivotally supported anarmature 43, tapered at each end to 'reduce its mass. The armature i3 ismounted on an elongated bar it preferably of a suitable aluminum alloyand is provided with recesses for receiving knife edges upon which it ismounted. The bar 14 is held on its pivots and the armature l3 balancedpreferably by means of a resilient support- The bar aid is turned atright angles and has secured to its other end a stylus holder QT inwhich is mounted a stylus cutter 48.

For further details concerning the construction and operation of therecording, mechanism just described, reference should he had to PatentNo. 1,663,884, of H. C. Harrison, issued March 27, 1928.

The stylus cutter 48 engages a wax record blank 50 which is supported bya drum 51 to which power is communicated from motor 52.

Referring to Fig. 2 the mechanism for retransmittmg the reproduction ofthe matter recorded on the record 50, the transmission of currentcharacteristics over the telephone circuit 59 in accordance with thecuttings on the record and the reproduction of the picture at a distantstation'will now be described. As shown in Fig. 2, the reproducingmechanism.55, which may be of a similar construction to that previouslyde- V imam This may beithesiame speed as the speed of the motor drivingthe cylinder during the recording operation or some otherspeed differentfrom the speed at which the picture was originally recorded as will bepointed out later. Withthese conditions satisfied the carrier currentwaves representing'not only the'modulated output carrier current wavebut also the synchronizing current wave will be impressed on the lineconductors 59 extending to station C.

The impulses upon being received at sta-' tion C pass through a terminalrepeater 67 and are impressed on the picture channel filter 68 ,and thecontrol channel filter 69. Each of these two filters passes only aparticular frequency which performs the desired function. The currentpassed by the control channel filter is amplified and rectified by meansof an amplifier-rectifier 70 and impressed on a secondary fork or speedcontrol element 71. The secondary fork 71 thus operates at a definitespeed ratio with reference to the master-fork located at release of the.startin station A and serves to drive the motor 72 so that the recordingdrum will rotate at the desired speed. s

Similarly, the motor72 is connected with the, reproducing mechanism'through astarting mechanism 73. The starting mecha- IllSIIl 73 ispreferably the same as'that described at station A. Since thisparticular part does not form a part of the present invention, furtherdetails thereof are believed unnecessary.

The drum 65 which is driven from the motor 72 throu h suitable gears hasmounted thereon a p otosensitive surface or film 66. Connected to thepicture channel filter 68 is an amplifier 74 servin to control the mecanism 73 and the operation ofa suitable light valve 75. The light valvecontrols the amount of light fallingcn the sensitive surface 66 from alight source 76 in accordance with the signals received thus reproducingthe picture.

The operation of the system will now be described. Assume that's,transparency 29 of a picture to be transmitted has been secured to thedrum 14. When it is desired to start the transmission, suitablemechanism is operated for releasing the starting mechanism 22. .Theoperation of this mechanism not only releases shaft 20 for rotatiombutalso transmits to station B a carrier current .wave which is im ressedon the electrical recorder 36 and w 'ch is recorded on the record 50.The drum 14 and the trans arent film are now rotated and moved axiallyby means'of the motor 21 whichis driven from the master foil: 25.Carrier current modulated in accordance with the current anpressed onthe amplifier-modulator 6, as determined by the condition of thephoto-electric cell 8, passes through the picture channel filter 9 andis impressed on the terminal repeater 11. Simultaneously, with the im-.

pression of the picture carrier current wave on the terminal repeater11, a second car-- rier current wave of a different frequency, asdetermined by the control channel filter 27, is impressed on theterminalrepeater.

The two carrier current waves are transmitted over the line conductors10 to station B where they pass through theterminal repeater 33 andamplifier 34 and are impressed on the control-element 35. of theelectransmitted to the station B and permanently recorded on the recordblank 50.

Assume for example, that it is desired to transmit a picture inaccordance with the one previously recorded on the record blank 50 to adistant station C.- The record blank 50 is accordingly secured to thedrum 56 which is driven by the motor 57. The motor is now startedand'the stylus 58 allowed to traverse the cuttings in the record 50. The

operation of thestylus 58 causes the conversion' of the mechanicalmovements thereof.

through the action of the coils 45 and 46 into electrical energy havingthe same characteristics as that controlling the recording-opera 165tion. Carrier current waves are accordingly impressed on the lineconductors 59 throng an amplifier 60 and a terminal repeater 61. Theimpulses received at station 0 from line conductors 59 pass throughterminal repeater'67 where they divide, the picture carrier currentpassing through the picture. channel filter 68 while the synchronizingcarrier current passes through the filter 69. At the beginning of therecord 50 as previously described, there is recorded a control frequencycurrent which acts on the ampli* fier'74 to cause the o eration of thestarting v mechanism 73 for re easing the drum 65 for rotation. Thepicture carrier currents are amplified by means of the amplifier 7 4 andimpressed on thelight valve-7 5 which controls the exposure of thevarious elemental areas of the light sensitive surface 66 1 n accordancewith the tone values of the original picture, The synchronizing carriercurrent waves are amplified by means-of the amplifier. 70, and controlthe secondary fork 71' so that the motor 72 rotates and moves the drum65 at the same speed relative to the speed of picture signal transmisionas that at which the drum 14 located at station A moved. Consequently,the respective ole mental areas of the light sensitive surface 66 willbe accordingly arranged and exposed to faithfully reproduce the originalpicture.

The speeds of recording and retransmitting signals do not necessarilybear any relation to each other as it is possible to receive signals atone speed and retransmit at some other speed as desired, providing thereproducing drum is rotating at a correspondingly different speed. Forexample, a transmitting cylinder at station it. may be rotating at aspeed ct one revolution per second and signals may be transmitted with a1300 cycle carrier. at the receiving station the recording elementmayrotate at the same speed or slower or faster as desired. Butcontinuing the example, we may consider that the recording drum rotatesat hall the speed the transmitting cylinder, that is, once every twoseconds. or once for each two revolutions of the cylinder at station A.This is possible since the special relation of the signals on the recordis immaterial, the proper sequence only being necessary. It now inretransmitting the signals the record is rotated at one revolution persecond which is twice its recording speed, the signals will betransmitted to the line at twice the original speed of recording and thecarrier will appear as 2600 cycles per second instead of l300'cycles asoriginally transmitted from station A. If. however,

there is no transmission channel available for transmitting 2600 cyclemodulated carrier, the speed of the record may be in.- creased ordecreased to any desired speed in order to make use of an availablechannel or to transmit signals at a "frequency at which the particulartransmission channel is most elficient. The recording element maytherefore receive and retransmit at any speeds whatever so that signalscan readily be transferred from carrier frequency to voice frequency orvice versa or may even be transmitted at speeds suitable for cabletransmission;

While the invention has been described as suitable for recordingsimultaneously both picture signals and synchronizing signals it maybedesired to transmit either type of signalby'itself. In this case thedanger of interference betweenthe picture signals and 1 svnchronizingsignals will be eliminated.

' The picture transmitting drum may then be rotated by some constantfrequency motor and thevspeed ofr'otation indicated to station B so thaton" retransmission it will sim-' ply be necessary to tell the operatorat station (1 the ratio'of the speed of the recorded signalsto-thetransmitted signals in As illustrated inFig. 5 a number of sepa-;

rate sets of picture transmission apparatus may be connected to the sameline for trans mitting more than one picture at a time orforsimultaneously recording severalpictures on one record forsimultaneous retransmission. For this purpose two sets of transmissionapparatus and 83. which are preferably the same as that included withinthe dotted rectangle of Fig. 1, both transmit signals impressed to thesame line L through terminal repeaters 81 and 84 and filters 82 and 85.The two series of signals will of course be transmitted as modulationsof different frequency carrier waves. As shown the synchronizing signaloscillator and filter have been omitted but it is equally possible tooperate the system including the synchronizing channels. According tothis system of operation the signals from both on separate records. Sucha system is particularly adapted for use in transmitting coloredpictures in the form of three color records.

Although the invention has been described and discussed with referenceto a particular system, it should be understood that the invention isnot limited to use with the particular apparatus illustrated, but may beused in connection with the recording and retransmitting of any type ofelectrical signals.

The term light, as used herein includes not only radiations within thevisible'spectrum but also radiations having wave lengths above and belowthose of the visible spectrum.

It is to be understood that the terms used herein in reference topicture transmission,

.bothin the specification and claims, do not limit this invention to theproduction of a picture record at the receiver from 'a picstill ormoving picture or object is produced at the receiver, as in certainforms of tele- I vision systems.

What is claimed is: 1. In a picture transmission system, means forproducmg a record 1n accordance with modulations of'a'carrier wave asdetermined by the elemental tone values of a picture or object and inaccordance with a separate'carrier wave, a transmission line, and meansassociated with said line for reproducing from said record electricalvariations of the same forms as. those of said record.

neeaaaa 2. In a picture transmission system, means for transmitting a.carrier wave modulated in accordance with the tone characteristics of apicture or object, means for recording said carrier wave on a recordblank 1n the form of a single continuous impression, and

a reproducer for retransmitting the carrier wave ln accordance with theimpression on said record blank.

for converting electrical variations into mechanical vibrations inaccordance W1tl1 the elemental tone values of a picture or chject areceiving surface, means for causing sa1 vibrations to effect animpression on said surface to correspond to said electrical variations,a transmission line, and an electrical .reproducer for transmittingvtosaid line a carrier wave of the form determined by the impressions onsaid surface.

4. In a picture transmission system,.means for modulating a carriercurrent in accordance with elemental tone values of a picture or object,a line, means for impressing said carrier cuig'ent on said line and forsimultaneously impressing on said line a synchronizing carrier current,a receiving station with a receiving surface associated with said line,and means at said station responsive to .the transmission of saidcarrier currents over said line for producing a continuous impression insaid surface corresponding to the transmitted carrier currents.

5.In a picture transmission system, a transmission line, means forsimultaneously impressing on said line picture currents andsynchronizing currents, and means for receiving said currents andrecording the same in the form of a single continuous wave ofsubstantially sine form.

' 6. In a signaling system, a transmitting medium, means forsimultaneously impressing a plurality of carrler waves of diflerentfrequencies on said medium, a receiving sur-[ face, and means forrecording said simultaneously transmitted waves as a single continuousvariation in said surface.

7.. In a picture transmission system, means for making a record'in'theform of a single continuous wave of combined picture and synchronizingcurrents, and means for reproducing a picture from said single waverecord.

8. In a signalingsystem, sending appalratus, receiving apparatus, meansfor s multaneously sending picture currents and synchronizing currents,means for making a record inthe ,form of a "single continuous wave ofthe combined synchronizing and picture, currents, andmeans forreproducing a or picture on apparatus 3. In a picture transmissionsystem, means my name thisthir'd 192 5.

control of said single continuous wave record. I 9. In asignalingsystem, sending apparatus, receiving apparatus, means fortransmittin from said sending apparatus at a desire nizing currents,means for making a record of the combined signaling and synchronizingcurrents, means controlled by said record for retransmitting saidcurrents at any defrequency, signaling and synchro-' sired frequency,and means controlled by said ing at an desire speed a singlemechanicalrecordo the combined currents, means for retransmitting saidcombined currents under control of said record at any speed determinedby the transmission line characteristics, and means. for reproducing apicture from said retransmitted currents. y

12. In a picture transmission system, means for producingrpicturecurrents in accordance with the characteristics ofa picture or object, asource of carrier current of a particular frequency, means formodulating the current from said source by means of the picturecurrents, means for making a. record of the modulated carrier current,means controlled by the form of said record for reproducing a modulatedcarrier current of any desired frequency, and means-controlled by saidreproduced current for reproducing said picture. I. I

13. In a picture transmission .system,

means for producing at a particular fre- 'quency currents varying inaccordance with the characteristics of a picture orobject, a receivingsurface, means for changing said current variations into mechanicalvibra-- I roduce'a record thereof in the substance 0 said receivingsurface, a current tions to generator controlled by said record forreproducing said current variations at any desired frequency to reroduce said picture.

In witness whereof I hereunto subscribe 5 CAROLE e.

day, of August D.,

